diff --git a/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/InteropServices/Marshal.NativeAot.cs b/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/InteropServices/Marshal.NativeAot.cs
index ff98d77ee098ce..f354e92fcd9aca 100644
--- a/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/InteropServices/Marshal.NativeAot.cs
+++ b/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/InteropServices/Marshal.NativeAot.cs
@@ -20,7 +20,7 @@ internal static int SizeOfHelper(RuntimeType t, bool throwIfNotMarshalable)
         {
             Debug.Assert(throwIfNotMarshalable);
 
-            if (t.IsPointer /* or IsFunctionPointer */)
+            if (t.IsPointer || t.IsFunctionPointer)
                 return IntPtr.Size;
 
             if (t.IsByRef || t.IsArray || t.ContainsGenericParameters)
diff --git a/src/libraries/System.Runtime.InteropServices/tests/System.Runtime.InteropServices.UnitTests/System/Runtime/InteropServices/Marshal/SizeOfTests.cs b/src/libraries/System.Runtime.InteropServices/tests/System.Runtime.InteropServices.UnitTests/System/Runtime/InteropServices/Marshal/SizeOfTests.cs
index 2d0c0b2b93d8a4..538b323a433923 100644
--- a/src/libraries/System.Runtime.InteropServices/tests/System.Runtime.InteropServices.UnitTests/System/Runtime/InteropServices/Marshal/SizeOfTests.cs
+++ b/src/libraries/System.Runtime.InteropServices/tests/System.Runtime.InteropServices.UnitTests/System/Runtime/InteropServices/Marshal/SizeOfTests.cs
@@ -31,6 +31,12 @@ public void SizeOf_Object_ReturnsExpected()
             Assert.NotEqual(0, Marshal.SizeOf(typeof(SomeTestStruct)));
         }
 
+        [Fact]
+        public unsafe void SizeOf_FunctionPointer_ReturnsExpected()
+        {
+            Assert.Equal(IntPtr.Size, Marshal.SizeOf(typeof(delegate*<void>)));
+        }
+
         [Fact]
         public void SizeOf_Pointer_ReturnsExpected()
         {